The present invention relates to a rotation plate that detects a rotational position of an output shaft or the like and a motor that supplies power in correspondence with the rotational position detected by the rotation plate.
A motor used as a drive source for a vehicle wiper device includes a motor unit and a deceleration unit. The motor unit is supplied with power to drive and rotate a rotation shaft. The deceleration unit decelerates the rotation generated by the motor unit and outputs the decelerated rotation. The motor unit and the deceleration unit are coupled integrally with each other. The deceleration unit accommodates a worm wheel, which forms a deceleration mechanism, and an output shaft, which rotates integrally with the worm wheel. A wiper is coupled by a link mechanism to the output shaft.
In such a motor, when a wiper switch is switched OFF to stop the wiper during a wiping operation, it is desirable that the wiper be operated to a predetermined stop position and stopped at the stop position. Thus, the motor accommodates a rotation plate in the deceleration unit to detect the rotational position of the output shaft and supply power to the motor unit in accordance with the position of the wiper, that is, the rotational position of the output shaft (refer to, for example, Japanese Unexamined Utility Model Publication No. 55-56753).
The rotation plate is formed by fixing a planar movable contact plate, which is punched out into a predetermined conductive pattern from a conductive plate material, to a holding member, which is formed from an insulating material. The rotation plate is circular. The rotation plate is formed to be rotatable with the worm wheel. A plurality of fixed contact terminals that slide in contact with the movable contact plate side surface (i.e., front surface of the rotation plate) of the rotation plate is accommodated in the deceleration unit. In the motor, the rotational position of the output shaft is detected based on contact positions of the fixed contact terminals with the rotation plate.
When the front surface of the movable contact plate projects outward in the axial direction of the motor from the front surface of the holding member, the movable contact plate forms a step on the front surface of the rotation plate, on which the fixed contact terminals slide. Thus, the fixed contact terminals come into contact with a corner formed in the edge of the movable contact plate when sliding from the front surface of the holding member to the front surface of the movable contact plate or when sliding from the front surface of the movable contact plate to the front surface of the holding member. This results in early wear of the fixed contact terminals. Thus, to suppress wear of the fixed contact terminals, a recess shaped in conformance with the movable contact plate and having a depth that is greater than or equal to the plate thickness of the movable contact plate is formed in the front surface of the holding member. The movable contact plate is arranged in the recess. This prevents the front surface of the movable contact plate from projecting outward from the front surface of the holding member. However, the stop position of the wiper or the wiping angle (swing range) of the wiper is set in accordance with the vehicle type. Thus, there are various shapes of conductive patterns, which are set in accordance with the stop position of the wiper or the wiping angle of the wiper. The movable contact plate including the conductive pattern may be formed with any of a variety of shapes in accordance with the vehicle type. Accordingly, a holding member that includes the recess to which the movable contact plate is fixed is also manufactured to have any of a variety of shapes in accordance with the shape of the movable contact plate. For instance, when forming different types of holding members with an insulating resin material, plural types of molds are required to forming the holding members. This increases the manufacturing cost of the rotation plate.
It is an object of the present invention to provide a rotation plate, which reduces manufacturing costs, and a motor, which includes the rotation plate.
To achieve the above object, one aspect of the present invention is a rotation plate including a surface. A fixed contact terminal slides in contact with the surface of the rotation plate. The rotation plate includes a movable contact plate and a holding member. The movable contact plate forms a predetermined conductive pattern. The holding member holds the movable contact plate. The holding member is formed from an insulating resin material. The movable contact plate and the holding member are molded integrally and fixed to each other so that a surface of the movable contact plate is exposed and does not project outward from a surface of the holding member.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.